/******************************************************************************
 * Qwt Widget Library
 * Copyright (C) 1997   Josef Wilgen
 * Copyright (C) 2002   Uwe Rathmann
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the Qwt License, Version 1.0
 *****************************************************************************/

#include "qwt_sampling_thread.h"
#include <qelapsedtimer.h>

class QwtSamplingThread::PrivateData
{
public:
  QElapsedTimer timer;
  double msecsInterval;
};

//! Constructor
QwtSamplingThread::QwtSamplingThread(QObject *parent)
  : QThread(parent)
{
  m_data = new PrivateData;
  m_data->msecsInterval = 1e3; // 1 second
}

//! Destructor
QwtSamplingThread::~QwtSamplingThread()
{
  delete m_data;
}

/*!
   Change the interval (in ms), when sample() is called.
   The default interval is 1000.0 ( = 1s )

   \param msecs Interval
   \sa interval()
 */
void QwtSamplingThread::setInterval(double msecs)
{
  if (msecs < 0.0)
    msecs = 0.0;

  m_data->msecsInterval = msecs;
}

/*!
   \return Interval (in ms), between 2 calls of sample()
   \sa setInterval()
 */
double QwtSamplingThread::interval() const
{
  return m_data->msecsInterval;
}

/*!
   \return Time (in ms) since the thread was started
   \sa QThread::start(), run()
 */
double QwtSamplingThread::elapsed() const
{
  if (m_data->timer.isValid())
    return m_data->timer.nsecsElapsed() / 1e6;

  return 0.0;
}

/*!
   Terminate the collecting thread
   \sa QThread::start(), run()
 */
void QwtSamplingThread::stop()
{
  m_data->timer.invalidate();
}

/*!
   Loop collecting samples started from QThread::start()
   \sa stop()
 */
void QwtSamplingThread::run()
{
  m_data->timer.start();

  /*
      We should have all values in nsecs/qint64, but
      this would break existing code. TODO ...
      Anyway - for QThread::usleep we even need microseconds( usecs )
   */
  while (m_data->timer.isValid())
  {
    const qint64 timestamp = m_data->timer.nsecsElapsed();
    sample(timestamp / 1e9); // seconds

    if (m_data->msecsInterval > 0.0)
    {
      const double interval = m_data->msecsInterval * 1e3;
      const double elapsed = (m_data->timer.nsecsElapsed() - timestamp) / 1e3;

      const double usecs = interval - elapsed;

      if (usecs > 0.0)
        QThread::usleep(qRound(usecs));
    }
  }
}

#if QWT_MOC_INCLUDE
#  include "moc_qwt_sampling_thread.cpp"
#endif
